Xeljanz (tofacitinib) has a half-life of about 3 hours for the standard tablet and roughly 6 hours for the extended-release version. In practical terms, more than 95% of a dose is eliminated from your body within 24 hours. After about 18 to 24 hours, blood levels of the drug drop to trace amounts for most people.
Half-Life and Full Clearance
A drug’s half-life is the time it takes for the concentration in your blood to fall by half. For the immediate-release 5 mg tablet taken twice daily, that’s approximately 3 hours. The extended-release 11 mg tablet, taken once daily, has a half-life of about 6 hours because it releases the drug more slowly.
Pharmacokinetic data from healthy volunteers shows that more than 95% of a dose is cleared within 24 hours. Using the standard rule of thumb (five half-lives for near-complete elimination), the immediate-release tablet reaches negligible levels in roughly 15 hours, while the extended-release version takes closer to 30 hours. Either way, the active drug is essentially gone within a day or so of your last dose.
How Your Body Processes Xeljanz
Your liver does most of the heavy lifting. Tofacitinib is broken down primarily by a liver enzyme called CYP3A4, with a smaller contribution from another enzyme called CYP2C19. The resulting breakdown products, along with some unchanged drug, are then filtered out through your kidneys. In a study tracking where the drug ends up after a dose, about 80% was recovered in urine (29% as the original drug, the rest as breakdown products) and roughly 14% was recovered in stool.
Because the liver is the main clearance route, anything that affects liver function can change how quickly the drug leaves your system.
Factors That Slow Clearance
Several things can keep Xeljanz in your body longer than the typical 24-hour window.
- Kidney or liver problems. Since both organs play a role in processing and excreting the drug, impairment in either one can raise blood levels and extend clearance time. Dose reductions are standard for people with moderate to severe kidney disease or moderate liver disease.
- Other medications. Drugs that block the CYP3A4 enzyme slow your liver’s ability to break down tofacitinib. Strong CYP3A4 inhibitors (like the antifungal ketoconazole) or combinations that block both CYP3A4 and CYP2C19 (like the antifungal fluconazole) can significantly increase how much drug stays in your bloodstream and for how long. If you take any of these, your prescriber will typically lower the Xeljanz dose to compensate.
Age, weight, gender, and race do not meaningfully change how fast you clear the drug once differences in kidney function are accounted for. So an older adult with healthy kidneys eliminates Xeljanz at roughly the same rate as a younger adult.
How Long the Effects Last After Stopping
Even though the drug itself clears quickly, you might wonder how long its effects on your immune system linger. Xeljanz works by suppressing certain immune signaling pathways, and clinical trial data shows that disease activity can increase rapidly after stopping the medication. This suggests the immune suppression reverses fairly quickly once blood levels drop, likely within a few days.
This fast reversal is actually the reasoning behind current surgical guidelines. The American College of Rheumatology recommends stopping Xeljanz at least 3 days before elective joint replacement surgery, with the procedure scheduled on day 4 after the last dose. That window is enough for both the drug and its immunosuppressive effects to clear, reducing infection risk during surgery while keeping the medication-free period as short as possible to avoid disease flares.
Immediate-Release vs. Extended-Release
The two formulations deliver the same total amount of drug over 24 hours, just on different schedules. The immediate-release tablet hits peak blood levels in about 1 hour, while the extended-release version peaks at around 4 hours. Because the extended-release tablet releases tofacitinib more gradually, its half-life is roughly double that of the immediate-release form.
In terms of total clearance after your last dose, the difference is modest. The immediate-release version may be fully gone a few hours sooner, but both formulations reach negligible levels within about a day. If you’re stopping the medication for a specific reason, like an upcoming procedure, the 3-day pre-surgery guideline applies to both versions.